Improvement in bridges



Y PMENTED AUG'22 1871 e I i .a.

UNITED STATES GEORGE C. MORGAN, OF CHICAGO, ILLINOIS.

IMPROVEMENT IN BRIDGES.

Specification forming part of Letters Patent No. 118,258, dated August22, 1871.

To all whom t may concern:

Be it known that I, GEORGE C. MORGAN, of the city of Chicago, in thecounty of Cook and State of Illinois, have invented certain new anduseful Improvements in the Construction of Bridges, of which thefollowing is a full description, reference being had to the accompanyingdrawing making a part of this specification, in which- Figure lrepresents a side elevation; Fig. 2, a vertical cross-section 5 Fig. 3,a top or plan view; Fig. 4, ahorizontal section; Fig. 5, a detail,showing the method of tightening the braces, &c.; and Fig. 6, a sectionof the cable forming the lower cord.

My improvements relate to that class of bridges usually known as trussedbridges 5 and their nature consists in the application of wire-ropes orcables to the construction of truss-bridges, in the mode of tighteningor straining them, and in an improved construction of the lower cables.

To enable others skilled in the art to make and use my invention, I willdescribe its construction and application with reference to the drawing,in which-- A represents the upper cords; B, the posts; C, the bases oi'the posts; I), the side braces 5 E, the lower cords; F, the upperbrace-rods or cords; G, the upper cross-ties; H, the lower cross-ties;I, the lower brace-rods or cords; a, a triangular block or cap laid onor partially let into the upper cord; b, a plate laid on the cap a, towhich one end of a brace is firmly secured; c, screws by which thebraces are tightened; d, similar plates without tightening-screws; ande, eyes or eyebolts through which the cords or ropes F and I pass, or towhich they are attached. The upper cords A are made of cast plate orbariron, or other suitable material,as are also the posts B and thecross-ties G and H, and of any desired size, form, and dimensions, as myimprovements are designed to be applied to trussed bridges of anyconstruction. The lower cords E are made of a single or double wire-ropeor cable, as shown at Fig. 4, which passes the entire length of the spanand through the base C of each post, as shown, and are properlysecuredor anchored at the ends. In making the cables for this cord I insertadditional strands or wires, varying in length at the middle so as toincrease it in size and strength at that point, and from that pointdiminish it gradually toward each end. The

bases C of the posts are made for convenience in horizontal sections,and are secured together by means of suitable screws or bolts, and thesections are provided with suitable grooves and holes for inserting andsecuring the cords and braces. The braces I), F, and I are all made ofwire-ropes or cords. The side bracesD are irrnly secured at the bottomto the bases C and pass through the upper cord A, and, when not usedwith a tightening-plate, are firmly secured to the cord under the cap abut when used with a tightening-plate, b, they also pass through the capa, and are rmly secured to a fasteningplate, b, and are tightened orstrained by means of the screws c, and when sufficiently strained tomake the rope stiff, like a rigid rod or bar, keys or Wedges are drivenbetween the plate b and the cap a, when the screws may be removed orleft as desired.-

In order to apply the braces F I attach eyes or eyebolts e to the cord Aabove each cross-tie or beam G, as shown at Fig. 3, and below the beamsH, as shown at Fig. 4, and pass the wirerope through these eyes so as tomake them of a continuous rope, and thereby equalize the strainthroughout the entire length of the bridge. The lower braces are appliedin the same manner through similar eyes attached to or made a part ofthe bases C below each beam or cross-tie H, and they are strained intoplace and held in position at the ends by means similar to that shownand described for tightening the braces D, or by any 'other suitablemeans, and these braces may be made to run the entire length of thebridge, or they may be applied in section. In order to attach ilooring,joists or stringers are laid along on the cross-ties or beams H and theliooring is spiked or nailed to them.

It is well known thatwire-rope is much stronger than solid iron of thesame size or weight. By its use, therefore, bridges or other structurescan be made of equal strength with much less weight of material, orofthe same weight of much greater strength. This methodbf trussing isalso applicable to trusses for roofs or other purposes.

I am aware that wire-ropes and cables have been heretofore used in theconstruction of suspension-bridges, and I do not, therefore, claim,broadly, their application to bridges..

What I claim as my invention, and desire to secure by Letters Patent',is-

l. The mode of tightening the vertical braces the middle and graduallytapered each Way and D by means of the plate b and screws c,substanapplied t0 a truss-bridge7 substantially as detally as specified.scribed.

2. The braces 0r stays F and I When made 00u GEORGE C. MORGAN.

tinuous and applied, by means of eyes so as to Witnesses: p v

make the strain uniform, substantially specified. E. A. WEST,

3. The Wire cords E when made enlarged at O. W. BOND.

